Device for feeding dense cellulosic pulp into a closed container

ABSTRACT

A means for fluffing cellulosic pulp that should be treated in a gaseous environment, e.g., bleached with a gaseous bleaching agent, consists of a rotary breaker inserted in an inlet chamber at the top of the container in which the treatment takes place. The breaker comprises a hub carried by a vertical shaft and a number of inclined vanes distributed over the cylindrical face of said hub and having serrated edges working upon a plug of pulp continuously fed into said inlet chamber through a horizontal conduit having its orifice opposite the breaker.

United States Patent i ht r 1 51 Feb. 22, 1972 [54] DEVICE FOR FEEDING DENSE [56] References Cited CELLULOSIC PULP INTO A CLOSED CONTAINER UNlTED STATES PATENTS 1,622,849 3/1927 Ruprecht et a1. ..24l/ 100 X [721 lnvemo Richter, Jean p 3,175,830 3/1965 Lepp ..241/186 x France 2,480,998 9/1949 Brackett. .....241/48 X 73 A r K Aka M K I 1,851,390 3/1932 Kehoe 241/280 X l 1 ss'gnee a aflstad' swede 2,391,480 12/1945 Ross et al... ..241/100 [22] Filed: Mar. 18, 1970 3,170,647 2/1965 Loftin ..241/280 [21] Appl' 20760 Primary ExaminerGranville Y. Custer, Jr. v

, AttorneyCushmar1, Darby & Cushman 30 Fore A 11 t' Pri r1 D ta l A 3 9 W a 57] ABSTRACT 1 69 pr Sweden 4834/69 A means for fluffing cellulosrc pulp that should be treated 1n a gaseous environment, e.g., bleached with a gaseous bleaching [521 US. Cl ..24l/48, 241/57, 241/186, age-mlconsists ofa rotary breaker inserted in an inlet chamber 241/280 at the top of the container in which the treatment takes place. [51 Int. Cl B07D 9/00 The breaker comprises a h i d b a -fl h f d a [58] Field of Search ..241/48, 57, 100, 186, 278, number f inclined vanes i i d over h li d i l fac 241/280 of said hub and having serrated edges working upon a plug of pulp continuously fed into said inlet chamber through a horizontal conduit having its orifice opposite the breaker.

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DEVICE FOR FEEDING DENSE CELLULOSIC PULP INTO A CLOSED CONTAINER The invention relates to the feeding of dense cellulosic pulp into a container wherein the pulp should be treated in gas phase, e.g., bleached with a gaseous bleaching agent. For this purpose it is important to disintegrate the pulp so that the gas can penetrate into the interspaces and pores of the fibers and fiber bundles and thus become evenly distributed in the pulp, and it is also important to spread the supplied pulp in order to have the same drop or temporarily hover in the atmosphere with the best possible contact therewith, before the pulp coalesces into a compact layer that is not so easily penetrated by gases.

The invention relates to a device suitable for this purpose, which is characterized in that a breaking means rotary about a vertical axis and having breaking teeth protruding from a hub is located in a vertical tubular inlet chamber upon the container and opposite to an aperture in the wall thereof, into which there opens an essentially horizontal conduit provided with a device for feeding pulp in the shape of a compressed plug continuously therethrough.

A preferred embodiment of the device according to the invention will be more closely described herein below'with reference to the accompanying drawing, in which FIG. 1 is a vertical sectional view of the upper end of a treatment container equipped with the device in question, and FIG. 2 is a vertical sectional view taken along the line "-11 in FIG. 1.

ln the drawing, ll designates an upright cylindrical container adapted for continuous bleaching of high-consistency cellulosic pulp with a gaseous bleaching agent, e.g., chlorine dioxide. On the top of the container there are provided a central pulp inlet 13 and a gas inlet 15, and at the bottom (not shown) of the container there are discharging means by which the treated pulp is discharged, so that the pulp moves continuously downwards through the container. The container is gastight and possibly pressure resistant so that it can be maintained under an overpressure of the order of atmospheres. lf desired, the same is also provided with heating means, e.g., conduits for supply of live steam. Of course, pressures and temperatures used are depending upon the nature of the gaseous bleaching agent.

Connected to the inlet 13 is a vertical tubular chamber 17, in the upper part of which a breaker 19 is located. Said breaker is attached to the overhanging lower end of a vertical shaft 21 extending through a lid 23 upon said sleeve,journaled in bearings 25, 27 and driven via ropes by an electric motor 29.

[n the sidewall of the tubular chamber 17 there opens a horizontal conduit 31 through which dense pulp with a dry' content of, e.g., l5-30 percent is fed by means ofa volumetric pump 33. preferably of the kind described in the Swedish Pat. No. l95,77 1. ln the conduit 31 and after the pump there is inserted a shutting-off valve 35 in order to be able to prevent backflow during possible work stops.

The breaker 19 consists of a cylindrical hub 37 and a number of vanes 39 extending radially therefrom and having a series of breaking or tearing teeth 41 shaped in their outer edges. Said vanes are distributed over the cylindrical face of the hub in the axial as well as in the circumferential direction and are fastened to the hub in an oblique position so that they form an angle of, e.g., 45 with the axis of the breaker. All

breaking teeth are situated at about the same radial distance from the axis of rotation and move quite close to the wall of the tubular chamber 17. The breaker is placed opposite to the orifice of the conduit 31 and the teeth rows overlap in the axial direction so that the entire orifice area is swept over by the breaking teeth.

On account of the high consistency of the pulp and the friction in the conduit 31 the pulp is fed through said conduit in the shape of a compact and coherent pulp plug. According as said plug emanates through the orifice in the wall of the verti' cal tubular chamber 17, the same is worked upon by the breaking teeth which loosen the fiber material and divide the same into flocks that are whirled around by the breaker so that they move in a helical path down through the lower part of the tubular chamber and are then spread into the container 11. During said movement the pulp flocks are brought into intimate contact with the gas atmosphere so that they absorb therefrom a substantial part of the gas required for the following bleaching reaction. Further down in the container the pulp is collected as a layer which, on account of the loose shape of the pulp, allows gas to glow therethrough in order to supply a further amount of bleaching agent to the pulp.

FIG. 1 shows a return conduit 45 in which a pump 43 is inserted and through which gas taken from the container is returned to the upper end of the tubular chamber 17. In this manner a faster relative movement of pulp flocks and bleaching gas is effected, which favors the penetration of the gas into the cavities of the fiber material. A screen 47 serves to prevent the pulp flocks from entering said conduit 45.

I claim:

1. Apparatus for bleaching cellulosic pulp which comprises a bleaching vessel, means for supplying gaseous bleaching agent to said vessel at high pressure, a vertical tubular pulp inlet at the top of said vessel, an essentially horizontal conduit with a discharge opening into the upper part of said tumbler inlet, pump means for supplying dense pulp through said horizontal conduit to said tubular inlet for discharge into said vessel, breaker means positioned in the upper part of said inlet and rotary about a vertical axis, said breaker means including breaking teeth sweeping across the entire face of said discharge opening so as to loosen pulp discharged therethrough, and means for maintaining a flow of said gaseous bleaching agent through the pulp in said inlet, said lastnamed means comprising a conduit member discharging into said tubular inlet at a point above said breaker means whereby pulp during its passage through the lower part of said inlet for discharge into the vessel is whirled around in intimate contact with the bleaching gas.

2. Apparatus according to claim 1, characterized in that the breaking teeth are formed in the outer edges of a series of equal vanes which are mutually displaced axially and circumferentially and the inner edges of which are attached to the hub in such a position as to be radially directed and form an angle to the axis of rotation.

3. Apparatus according to claim I wherein the means for supplying pulp through said horizontal conduit comprise a volumetric pump 'and means for maintaining gas flow in said inlet comprises conduit means connecting the top of said vessel with the upper part of said tubular inlet above said breaker means, and pump means for pumping gaseous bleaching agent from the top of said vessel through said inlet via said conduit means. 

2. Apparatus according to claim 1, characterized in that the breaking teeth are formed in the outer edges of a series of equal vanes which are mutually displaced axially and circumferentially and the inner edges of which are attached to the hub in such a position as to be radially directed and form an angle to the axis of rotation.
 3. Apparatus according to claim 1 wherein the means for supplying pulp through said horizontal conduit comprise a volumetric pump and means for maintaining gas flow in said inlet comprises conduit means connecting the top oF said vessel with the upper part of said tubular inlet above said breaker means, and pump means for pumping gaseous bleaching agent from the top of said vessel through said inlet via said conduit means. 